Exams › NEET › Physics

The self-inductance of a choke coil is 10 mH. When it is connected to a 10 V d.c. source, the power loss is 20 W. When it is connected to a 10 V a.c. source, the power loss is 10 W. The frequency of the a.c. source is:

1. 50 Hz
2. 60 Hz
3. 80 Hz
4. 100 Hz

Correct answer: 80 Hz

Solution

From the d.c. case, the coil’s resistance is found using \(P=V^2/R\). Then the a.c. power gives the impedance relation involving \(\omega L\). Solving for \(\omega\) yields the frequency as 80 Hz.

Related NEET Physics questions

• The current flowing through the resistor in a series LCR a.c. circuit, is I=ε / R Now the inductor and capacitor are connected in parallel and joined in series with the resistor as shown in figure. The current in the circuit is now. (Symbols have their usual meaning)
• Which of the following will not increase voltage in a simple generator?
• With increase in frequency of an A.C. supply, the inductive reactance
• ln an A C circuit, the instantanceous emf and current are given by e=100 sin 30 t, i=sin (30 t (π)/(4)) In one cycle of A C, the average power consumed by the circuit and the wattles current are, respectively
• The Joules heating effect for an electric heater in A. C and in D.C. circuit is
• A resistance (R)=12 Ω; inductance (L)=2 henry and capacitive reactance C=5 m F are connected in series to an ac generator, then:

⚔️ Practice NEET Physics free + battle 1v1 →